Optical character recognition devices of the type to which this invention relates, including the preferred embodiment described below, are within the state of the art and publicly known in various forms, except for the registration techniques upon which the invention herein is based.
In such systems a visual character, generally inscribed in ink or pencil on paper, is examined by a photoconductor. Typically, this optical examination will be by a line of photoconductors. At electronic speeds this image is digitized, stored in data processing memory as a binary pattern corresponding to the image, analyzed for registration information such as the extreme lower left point, and compared against a separate template or some equivalent for identification of the characters to be recognized.
Various known systems register the pattern at lower left, center, top right, top left, center of density, and other consistently identifiable points. Each of these known systems uses one form of registrations in its comparison against all of the templates or other recognition models. The invention disclosed and claimed here differs fundamentally from known prior art in that the registration point is varied for different identification models compared against an image being identified.
It is known to make multiple comparisons of an image against models for one character and to adjust the registration slightly for each comparison. Such adjustment is to give an average registration from one perspective. In accordance with this invention, the perspective itself is changed.
Improved accuracy is a basic design criterion in current optical character recognition systems. The theoretical differences in character forms are often obscured in practice by smears, dirt, aberrations and peculiarities of inscription, physical damage to the writing, and any one or combination of these and any of the other possible similar influences and imperfections too numerous to attempt to categorize. For such reasons characters which differ clearly when considered ideally may, when viewed in practice, appear substantially similar when compared in a character recognition device against a template or other recognition model. In fact, because of such uncertainties in practice, standard technique in the art requires more than minimal conformance to an identification model before a character is considered recognized or rejected.